Nontarnishing detergent compositions containing a water-soluble inorganic tantalate



N ONTARNISHING DETERGENT COMPOSITIONS CONTAINING A WATER-SOLUBLE INOR-GANIC TANTALATE Edgar E. Rulf, Bergenfield, and Elwin E. Smith, Paramus,N. J., assignors to Lever Brothers Company, New York, N. Y., acorporation of Maine No Drawing. Application June 28, 1956 Serial No.594,355

12 Claims. (Cl. 252135) This invention relates to detergent compositionscontaining tarnish inhibitors and more particularly to polyphosphatecompositions containing water-soluble inorganic tantalates as tarnishinhibitors.

Compositions containing polyphosphates are now widely used for detergentand other purposes. Aqueous solutions of polyphosphates tend, when atcertain pH values, to tarnish German silver (a nickel-zinc-copper alloy)to a variety of shades from yellow to bluish-black, especially if thesolutions are at elevated temperatures and are allowed to remain incontact with the alloy for several minutes. Since German silver isfrequently used forhousehold articles commonly washed inpolyphosphate-built detergent compositions, it is evident that this is aserious problem.

In accordance with the instant invention polyphosphate compositions areprovided containing a tarnish inhibitor which compositions inhibit theformation of tarnish upon German silver. The? tarnish inhibitors of theinvention are water-soluble inorganic tantalates, for example, so-' diumtantalate and potassium tantalate.

An amount of the water-soluble inorganic tantalate is added to thepolyphosphate composition which is suflici'ent to give tarnishinhibition when the composition is used in its normal Way. 'It will beunderstood that the amount required will depend in part upon the tarnishinhibiting properties of the particular tantalate in question, upon thetendency of the polyphosphate with which it is used to tarnish Germansilver, and upon the amount of the polyphosphate present. In general,therefore, at least about 4% of the water-soluble inorganic tantalatebased on the weightof the polyphosphate present in the detergentcomposition will inhibit the'formation of tarnish by the composition.The'maximum amount of the tantalate is not critical, but more than isnecessary to give, the desired effect will usually not be used, andofcourse an amount in excess of that soluble in an aqueous solution of thecomposition would not be used. In most cases, the maximum suggestedwould be about 15% based on the weight of polyphosphate.

The tarnish inhibitors of the present invention are effective withwater-soluble alkali metal polyphosphates with-- in the range of aboutpH 10 to about pH 11. The alkali metal polyphosphates may include, byway of example, pentasodium and pentapotassium tripolyphosphates,tetrasodium and tetrapotassium pyrophosphates, sodium and potassiumhexamethaphosphates, and hexasodium and hexapotassiumtetrapolyphosphates. 'There is no critical amount of alkali metalpolyphosphate which need be employed in the compositions, the amount ofpolyphosphate in' the compositions being dictated only by the optionalpresence of'organic nonsoap detergents and builders which might beincludecl'in the detergent compositions.

Examples of such additional optional components are organic nonsoapdetergents which may be either anionic, cationic, or nonionic detergentsand builders, water, and inert materials. These detergent compositionsmay contain alkali metal polyphosphate in any amount, usually icePatented Apr. 1, 1958 between 5% and 50%; conventional proportions ofnonsoap detergent, usually within the range between 5% and 40%; fromabout 4% to about 15% of a water-soluble inorganic tantalate based onthe weight of the polyphosphate; and the balance builders and inertmaterials.

The alkylaryl sulfonates are a class of anionic detergents which may beincluded in the detergent compositions. One example thereof is thesulfonated phenyl polypropylene alkanes', characterized by the branchedchain structure of polypropylene and a tertiary alkyl carbon at thehenzene ring, and having the following general structure:

. CHaRz SOsM where A is hydrogen or alkali metal, i. e., ammonium,sodium, or potassium, n is a small whole number fromone to about five,preferably two or three, R ishydrogen, or

an alkyl, aryl, or cycloaliphatic group, such as methyl, and R, is analkyl oralkylene radical, such. as myristyl, palmityl oleyl, andstearyl. Sodium palmitic tauride, sodiumpalmitic methyl tauride, sodiummyristic methyl tauride, sodiumpalmitic-stearic methyl tauride, andsodium palmitic methyl amidopropane sulfonate are typical examplesthereof.

These compounds are prepared by interacting the corresponding aliphaticacid anhydride or halide with an organic aliphatic aminosulfonic acid,such as taurine,

NH CH CH SO H, and the various N-substituted taurines,

such as N-methyl taurine, or aminopropane sulfonic acid, Hz( 2)a a Otherwater-soluble alkyl aromatic sulfonic acids may constitute optionalcomponents such as those prepared by alkylating benzeneor naphthalenewith a kerosene fraction followed by sulfonationto aliphatic sulfonicacids, esters of sulfuric acid withaliphatic alcohols of ten to eighteencarbon atoms, particularly those derived by the reduction of coconutoil, palm oil, and like long-chain fatty acids, sulfonated castor oil,esters and ethers of isethionic acid, long-chain fatty acid esters andlong-chain alkyl ethers of 2,3-dihydroxypropane sulfonic acid andsulfuric acid esters of monoglycerides and glycerol monoet'hers. Thesalts of these acids are ordinarily employed.

The tarnish inhibitors are also useful with nonionic detergentscontaining polyphosphates, such as alkyl oxyether and ester and.thioether and ester detergents having the following general formula:

where R isa straight or branched chain saturated orrune saturatedhydrocarbon group having 4 from eight to eighteencarbon. atoms... or.an. aralkyl group. having. a.

straight or branched chain saturated or unsaturated hydrocarbon group offrom eight toeightecn carbon atoms attached 'to the aryl. nucleus, andattached itoqi At; through. the :aryl nucleus, .A .is selected fromthehgroup, consisting. of ethereal oxygen and sulfur, .carboxylic:.ester and thiocarboxylic .ester groups andqx is anumber. fromzeightto.

twenty. R can, for example, bea straight or. branched:

chain octyl, nonyl, decyl, lauryl,.myristyl,.cetylror stearyl group, oran alkylaryl group such asoctylbenzene, nonylbenzene, decylbenzene,stearylbenzene, etc.

The sulfated ethoxynated derivatives of the abovealso are useful anionicdetergents:

Renex" (polyoxyethyleneester of talloil acids), Sterox.

CD and Neutronyx 330 and 331 (higher fatty acid esters of. polyethyleneglycol).

Where R is aralkyl, the detergent can be derived-from.

an alkyl phenol or thiophenol.

The ethoxynated alkyl phenols and thiophenols have the following generalformula:

where R is a straight or branched chain saturated or unsaturatedhydrocarbon group having at least eight carbon atoms up to approximatelyeighteen carbon atoms, A is,

oxygen or sulfur and x is a number from eight to twenty.

R can, for example, be a straight or branchedchain octyl,.

nonyl, decyl, lauryl, cetyl, myristyl, or stearyl group. Typical are thecondensation products of octyl and nonyl phenol and thiophenol with from8 to 17 moles of ethylene oxide, available commercially under the tradenames NIWZ Antarox A-400, Igepal CA and CO, Triton X,100, Neutronyx 600.and Tergitol NFXJ The optional. supplemental builders may be alkalimetal inorganic salts, typical examples of which include sodium andpotassium sulfates, sodium and potassium chlorides, sodium and potassiumsilicates, and sodium and potassium carbonates.

In addition to or instead of the above mentioned supplemental inorganicsalts, organic materials, such as carboxymethylcellulose may be used asbuilders.

The builder mixture is so chosen among alkaline, neutral, and acidicsalts that the composition obtained in an aqueous 0.14% washing solutionhas a pH of about. 10 or 11, since solutions which are more alkaline maybe irritating to the skin and tend to weaken some fabrics, particularlywoolens.

The detergent compositions of the invention inhibit the formation oftarnish upon German silver in either hard or soft water. It will beappreciated that the detergent compositions may exist in any dry form,such as drumdried or spray-dried detergent compositions, or may be inliquid form.

Thespolyphosphate detergent compositions may be: prepared' byconventional methods, as by blending the ingredients. thereotin anaqueous. solutionor u y nd. then drying the resulting mixture in a sprayor drum dryer at elevated temperatures. The tarnish inhibitor may beadded to the polyphosphate: composition in any stage of its manufacture,to the finished polyphosphatc composition, or to the polyphosphatesolution.

The compositions of'the. invention will be furtherillustrated by thefollowing examples wherein a typical watersoluble inorganic tantalate,namely potassium tantalate, was employed in theeompositions. Thepotassium tantalate was tested as a solution of potassiumtantalateprepared by fusing 0.25 gram of tantalum pentoxide with 2.0grams ofpotassium carbonate, cooling the melt, and dissolving theresulting potassium tantalate in 500 milliliters of water.

In these examplesthefollowingtest procedure was employed. Five grams ofa polyphosphate composition (or an .equivalent weight ofacomponentthereof wherelspecified).werc dissolved in 600 millilitersof'water. Onetenthzof this volume, or 60 milliliters, was placed in a200 milliliter beaker and the required volume of inhibitor solution:added. The volume of solution in the beaker wasmade up to milliliters.The final concentration of polyphosphate composition or component isequivalent to five grams whole composition per quart of water. The pH atroom temperature was adjusted to the desired level with sodium hydroxideor hydrochloric acid solutions. The solution was then heated to -165 F.,and placed in a water bath to maintain the temperature of the solutionat 160-l65 F. A German silver metal strip, one inch by six inches,cleaned with a Noxon metal polish, rinsed, and buffed with a cloth, waspartially immersed in the solution and allowed to remain for one-halfhour. At the end of that time, the strip Was removed, rinsed, dried witha cloth, and visually examined for tarnish. The efiectiveness ofthetarnish inhibitor was rated as follows:

No tarnish.

Interface stain only.

Barely noticeable tarnish.

Slight tarnish.

Moderate tarnish.

Considerable (heavy) tarnish. Severe, as when inhibitor is absent.

Examples l-Zbelow show that a water-soluble inorganic tantalateinhibitsthe formation of tarnish by a tripolyphosphate, such aspentasodium tripolyphosphate.

EXAMPLES l-2 Two separate; portions of pentasodium tripolyphosphate weredissolved in distilled water and to one there was added 6.7% ofpotassium tantalate (expressed as tanta lum .pentoxide) andthe volumesdiluted in accordance withthe: above. test procedure. Th pH of bothsolutions was; 11. Each, solution had a concentration of 2.25 grams. of.polyphosphate per: quart; of distilled water.

The. test. solution without; thepotassium tantalate.

or cationic, asrwell; as=supplemental builders inhibits the formationoftarnish, by such detergent compositions, This is. clearlyillustratedby the examples set forth be low wherein the: seven compositions ofTable I were employed.

Table l Compositions A B D E G Sodium Dodeeylbenzene Sulfonate.; 18.018.0 18.0 18.0 Laurie Ester of N-(beta-hydroxy-ethyl)-alpha- V V(chloropyridinium) acetamide [Emulsep l 18.0 18. 0 Pluronie L454 18.0Pentasodium Tripolyphosphate 45. 0 45. 0 45. 0 Tetrasodium Pyropbnsnhatn45. 0 45. 0 Sodium Hexametaphosphare 45. 0 HexasodlumTetrapolyphosphata; 45. 0 Sodium Sillcate 6. 0- 6.0 6.0 6.0 6.0 6. 0 6.0 Sodium Carbonate 3. 0 3.0 3.0 3.0 3. 0 3.0 3.0 SodiumGarboxymethylcellulo 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Water 10. 0 10.0 7.07.0 7.0 7.0 7. 0 Sodium Sulfate; 17. 17. 5 20. 5 20. 5 20. 5 20. 5 '20.5

Total k 100. 0 100. 0 100. 0 100. 0 100. 0 100. 0 100. 0

In Compositions A through G the amounts of the var- EXAMPLES 14-19 iouscomponents are expressed in percent by weight. Pluronic ll-.64 is anorganic (nonionic nonsoap detergent having the empirical formulaprepared by condensing ethylene oxide with a hydrophobic base formed bythe condensation of propylene oxide with propylene glycol where b. is aninteger selected from the group consisting of 26 to 30 and a plus 0 isan integer-such that the molecule contains from 40% to 50% of ethyleneoxide.

Examples 3-9 show that at least about 4% of a watersoluble inorganictantalate basedon the weight of polyphosphate inhibits the formation oftarnish by polyphosphate compositions containing an organic anionicnonsoap detergent and supplemental builders.

EXAMPLES 3-9 To five grams each of Compositions A and B there was addedpotassium tantalate in the proportions shown below and the testprocedure carried out with the following results. In Examples3-5 the pHof the test solution was 11, while in Examples 6-9 the pH of the testsolution was 10.

Percent Potassium Tantalate (expressed'as Tantalum Pentoxide)polyphosphate basis. 0. 0 3. 3 p 4. 4 6. 7 Grading (Composition A)(Examples 3-5)..." 6' 3 p 3 Grading (Composition B) (Examples (5-9)-...6 3 3 3 A water-soluble inorganic tantalate is effective as a tarnishinhibitor in polyphosphate compositions containing an organic nonsoapdetergent as well as supplemental builders when the. alkali metalpolyphosphate is other than tetrasodium pyrophosphate or pentasodiumtripolyphosphate, for example, sodium hexametaphosphate or hexa-' sodiumtetrapolyphosphate. This is clearly illustrated by Examples 10-13 setforth below.

EXAMPLES 10-13 Five grams each of Compositions F at pH 10 and G at pH 11per quart of distilled water tested in accordance with the testprocedure both tarnished German silver to a grading of 6, i. e., severetarnish. When 6.7% of potassium tantalate (expressed as tantalumpentoxide) based on the weight of polyphosphate was added to CompositionF, the tarnish grading of the composition upon Five grams each ofCompositions C and D (cationic detergents) and E (nonionic detergent)per quart of dis tilled water were tested in accordance with the testprocedure. Composition C having apH of 10 and Compositions D and Ehaving a pH of 11 all tarnished German silver to grade 6. When 6.7% ofpotassium tantalate (expressed as tantalum pentoxide) based on theweight of polyphosphate was added to each of these compositions, thethree compositions so produced then had a reduced tarnish grading at thespecified pH values of 4 for Composition C and 1 for Compositions D andE.

The amount of the alkali metal polyphosphate present in thepolyphosphate compositions may be as low as about 5% as noted above andas further illustrated by Ex- EXAMPLES 20-21 5% of pentasodiumtripolyphosphate was employed in Composition B with the amount of sodiumsulfate being increased to olfset the decrease in the pentasodiumtripolyphosphate content of the composition (40% additional sodiumsulfate). Five grams of this modified composition per quart of distilledwater at pH 10 had a tarnish grading of 4 upon German silver metal,whereas five grams of the modified composition per quart of distilledwater which also contained 6.7% of potassium tantalate (expressed astantalum pentoxide) based on the weight of polyphosphate at pH 10 had areduced tarnish grading of 2.

Examples 22-23 illustrate the fact that the watersoluble inorganictantalates are effective as tarnish inhibitors in polyphosphatecompositions when the poly-- phosphate compositions are used in hardwater. It will be noted that in all of the previous examples the waterwas soft water, i. e., distilled water.

EXAMPLES 22-23 Five grams of Composition B per quart of water having ahardness of p. p. m. at pH 11 tarnished German silver to grade 5,whereas five grams of Composition B containing 6.7% of potassiumtantalate (expressed as tantalum pentoxide) based on the weight ofpolyphosphate per quart of water having a hardness of 180 p. p. m. at pH11 tarnished German silver only to grade 1.

The effectiveness of water-soluble inorganic tantalates as tarnishinhibitors with liquid polyphosphate detergent compositions is clearlyillustrated in Examples 24-26.

EXAMPLES 24-7-26 Three five gram portions of the following liquiddetergent composition were dissolved separately in one quart ofdistilled water and potassium tantalate added thereto at theconcentrations indicated below. The tarnish grading of a strip of Germansilver metal inserted in each of the solutions at pH 10 is also setforth.

Composition Percent by Weight Potassium Dodecylbenzene Sultonate 10.Sodium Xylene Sulfonate 0.. 7.6 Laurie Isopropanolamide.--- 3.2 LaurieDlethanolamlde 3. 8 Tetrapotmslum Pyrophosphate I 20. 0 Sodium Slllmtp7, 0 Water---- 48. 4

Total 100.0

Example No-.-.' t 24 25 26 Percent Potassium Tantalata (expressed asTantalum Pentoxide), polyphosphate basis O. 0 7. 16.0 Tarnish Grade 6 33 It should be borne in mind that this invention relates to tarnishingand tarnish inhibitors and does not pertain 'to alkaline corrosion orcorrosion inhibitors. Tarnishing and corrosion of metals are two quitedissimilar phenomena. A discoloration is the principal manifestation oftarnishing, while a dissolving action characterizes corrosion of metal.Corrosion inhibitors are eaecnve because they remove oxygen fromthealkaline medium surrounding the metal being corroded. Theanti'tarin'shing action of a water-soluble inorganic tantalate on Germansilver, on the other hand, is due to a different mechanism, since thepresence of oxygen is not necessary tofthe tarnishing action ofpolyphosphates on German silver.

Obviously many. modifications and variations may be made in theinvention herein set forth without departing from the spirit and, scopethereof, and only such limitations should be imposed as are indicated inthe appended claims.

We claim:

1. A detergent composition consistingessentially of an alkali metaltripolyphosphate which in aqueous solution -tarnishes German silver anda water-soluble inorganic tantalate in an amount to lessen thetarnishing action of the polyphosphate.

2. A detergent compositionconsisting essentially of an alkali metaltripolyphosphate which in aqueous-solution tarnishes, German silver andfrom about 4% to about 15% of a water-solubleinorganic tantalate basedon the 4 weight of polyphosphate to lessen the tarnishing action of thepolyphosphate.

-soap detergent, and a water-soluble inorganic tantalate in an amountfrom about 4% to about 15% based on Y the weight of polyphosphate andsufficient to inhibit such tarnishing.

5. A detergent composition as set forth in claim 4 wherein thepolyphosphate is an alkali metal tripolyphosphate.

6. A detergent composition as set forth in claim 4 wherein thepolyphosphate is an alkali metal pyrophosphate.

7. A detergent composition as set forth in claim 4 wherein thepolyphosphate is an alkali metal hexametaphosphate.

8. A detergent composition as set forth in claim 4 wherein thepolyphosphate is an alkali metal tetrapolyphosphate. 7

9. A detergent composition as set ,forth in claim 4 wherein thewater-solubleinorganic tantalate is potassium tantalate.

10. A detergentcompoSitioh .as set forth in claim 4 wherein the organicn'onsoap detergent is an organic cationic nonsoap detergent;

11. A detergent composition as set forth in claim 4 wherein the organicnonsoap detergent is an organic nonionic nonso'ap detergent.

12. A detergent composition as set forth'in claim 4 wherein theorganiononsoap .1 detergent is an organic anionic nonsoap detergent.

References Cited in the fileof this patent UNITED STATES PATENTS2,303,399 Schwartz a... Dec. 1, 1942 2,419,805 Wegst Apr. 29, 19472,425,907 Wegst Aug. 19, 1947 2,618,604 Schaetfer Nov. 18, 1952 OTHERREFERENCES Smiths College Chemistry, William F. Ehret, 6th edition,1946, Periodic Classification of the Elements on inside back cover.

1. A DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF AN ALKALI METALTRIPOLYPHOSPHATE WHICH IN AQUEOUS SOLUTION TARNISHES GERMAN SILVER AND AWATER-SOLUBLE INORGANIC TANTALATE IN AN AMOUNT TO LESSEN THE TARNISHINGACTION OF THE POLYPHOSPHATE.